The use of Passive Integrated Transponder (PIT) tags which may be embedded in or attached to items to be tracked and accounted for has been widespread for some time. These commonly known PIT tag systems generally comprise one or more antenna coils so positioned as to generate a field of radiated electromagnetic energy within which the tagged item or object must pass. As generally deployed, such systems are used to track and/or count animals within which a PIT tag has been subcutaneously embedded or externally affixed. As the PIT tag traverses the radiated field of electromagnetic energy, it is energized in a manner known in the art. The PIT tag uses this energy--which is typically stored in a capacitive element--to power a transmission circuit which emits a unique PIT tag identification signal that is detected by the aforementioned antenna element. The identification signal detected by the antenna element is then transmitted to remote processing equipment which decodes the detected signal and uses this decoded information for the purposes of counting, tracking or otherwise maintaining records pertinent to the population of items or animals being tracked by said system.
These commonly known and used PIT tag interrogation systems suffer from a drawback heretofore unremedied in the art, that being the ability to remotely insure proper operation of the interrogation system. This shortcoming is particularly troublesome in applications where the antenna system is located in a remote location from the control point, or in locations which are physically difficult to access, such as, for example, underwater tunnels through which PIT-tagged fish travel for identification and tracking. The present solution for testing such systems is to have a user travel to the antenna location and physically pass a PIT tag through the antenna's radiated energy field so as to generate a tag signal detectable by the control unit. Successful receipt of the manually passed tag signal confirms that the system is operating properly. This present method of testing is expensive, resource intensive, and time consuming. Further, the difficulty in performing such an operation in fish tunnels placed underwater is obvious.
It would therefore be greatly advantageous for an apparatus or method to be developed which would alleviate the above identified shortcomings of the prior art. The present invention provides a solution.